This invention relates to a shaft sealing system for a rotary mechanical device requiring a shaft seal and more particularly to an improved sealing system including a split bushing seal element that is placed in a seal cavity or stuffing box of the mechanical device.
Rotary mechanical devices, such as mixers and centrifugal pumps include an impeller mounted on a shaft which is driven by an electrical motor. The shaft passes through a seal cavity or a stuffing box defined by a cylindrical cavity in the device housing. The shaft is supported by bearings at the motor end and seals are placed in the stuffing box to engage the shaft to prevent fluid from passing through the seal cavity and reaching the bearing and the motor, causing damage to both.
In mechanical pumps the seal cavity passes chemical fluids or solvents being pumped, many of which are corrosive. Accordingly, it is important that appropriate packing material is placed within the seal cavity. Seal water is pumped into the seal cavity through a flush port to prevent the fluid being pumped or mixed from travelling along the shaft to the bearings and motor and to provide lubricant to the packing. Over extended use, the pump shaft may develop a whip as the bearings wear. Thus, it is highly desirable to provide a sealing system that provides an effective seal and an additional bearing surface to reduce the whip that can occur as the shaft rotates thus controlling the amount of seal water entering a lantern ring groove in the seal cavity.
While there are a wide variety of devices available for use in providing a seal cavity bushing, it is desirable to provide a improved sealing system providing an additional bearing surface for the impeller end of the shaft and cause a reduction in the pumped or mixed fluid entering the seal cavity to be countered by the seal water and packing in order to provide advantages over available devices.
Generally speaking, in accordance with the invention, a shaft sealing system for a rotary mechanical device including a substantially rigid cylindrical bushing having an inner bore to be positioned over a shaft and at least one complimentary flexible packing ring to be inserted into the seal cavity and moved to the impeller end is provided. The rigid member is a cylindrical bushing including a lantern ring at the motor end. The inner bore provides a bearing surface for eliminating whip in the device shaft. The bushing is split to provide easy installation over an installed device shaft.
The bushing seal element in accordance with the invention is substantially rigid and is manufactured of a non-ferrous metal or filled thermoplastic material for providing an improved bearing surface and resistance to industrial solutions. The inner bore of the bushing closely approximates the outer diameter of the pump shaft. The motor end includes an internal groove and a corresponding outer groove with seal water openings to provide a lantern ring on the motor side of the bushing. Generally, two or three packing rings are added on the motor side to complete the installation.
Accordingly, it is an object of the invention to provide an improved shaft sealing system to be inserted into a seal cavity of a rotary mechanical device.
Another object of the invention is to provide an improved shaft sealing system for a rotary mechanical device including a rigid bushing member for supporting the impeller end of the device shaft.
A further object of the invention is to provide an improved shaft sealing system for a rotary mechanical device including a rigid bushing member having an integral lantern ring grove for controlling the amount of seal water entering the seal cavity.
Still another object of the invention is to provide an improved sealing system for a rotary mechanical device having an outer O-ring for improved isolation of the product being handled and seal water in the seal cavity.
Yet another object of the invention is an improved rigid seal bushing for use with complementary flexible packing rings for use in a shaft sealing system to be inserted into the seal cavity of rotary mechanical devices.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention comprises a product possessing the features, properties, and the relation of components which will be exemplified in the product hereinafter described and the scope of the invention will be indicated in the claims.